[Editor's note: I mentioned the arrest of technology editor David Mery in my recent Guardian column on Prism; he wrote in to correct some details and explain the astounding circumstances of how Britain's absurd war on terror caught him in its mesh for the crime of wearing a coat in the summer -CD]
I was observed directly when I entered Southwark tube station and then on CCTV. All the time it was by Met police officers. To my knowledge no computer algorithms were involved. In Naked Citizen, Patrick Hafner mixes the interview he did with me and some CCTV recognition algorithms, but the two are not directly related. The Met police officers at the entrance of the station were those who found my behaviour suspicious and decided initially to stop and search me under s44 of the Terrorism Act.
Who exactly took the decision to arrest me and the choice of legislation is less clear, as it appears that initially officers wanted to arrest me under the Terrorism Act but were overruled and decided on Public Nuisance (which can still carry a life sentence).
The Met and IPCC investigation files are still retained (until 2015 and 2014) but my police national computer record was deleted as well as my fingerprints and DNA, and I eventually also got the photographs back. The short version of the whole story is here.
That I let a tube train pass by without boarding it is the only important dispute in the police version of events and mine. That's the police version. Mine is that I tried to board the first train that arrived, but was then stopped by the police.